Q. Two tall buildings are 40 m apart. With what speed must a ball be thrown horizontally from a window 145 m above the ground in one building, so that it will enter a window 22.5 m from the ground in the other?
A) $5\ ms^{- 1}$
B) $8\ ms^{- 1}$
C) $10\ ms^{- 1}$
D) $16\ ms^{- 1}$
Explanation
(b) $h = 145 - 22.5 = 122.5\ m$
Now, $40 = v\sqrt{\frac{2 \times 122.5}{9.8}}$
or $40 = v \times 5\ \ or\ \ v = 8\ ms^{- 1}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.